Diffusion thermopower of metals

Abstract

The second order effect of the intrinsic two-phonon processes in the electron-phonon interaction gives rise to a new diffusion thermopower of metals. It is suggested that a higher order electron-phonon scattering process gives an additional term to the diffusion thermopower. In contrast to the Nielsen-Taylor effect (1970), such a process is given by the third order effect of the usual one-phonon processes. The absolute magnitude and temperature dependence of the additional term is, however, similar to the Nielsen-Taylor effect. Thus, in a quantitative study of the thermopower of metals, it is necessary to take into account the term suggested here as well as the Nielsen-Taylor term, the usual diffusion term and the phonon drag term.